Exploring factors determining resilience to marine heatwaves in coastal temperate rocky habitats

Coastal ecosystems, vital for global biodiversity and human well-being, face growing threats from climate change (CC), particularly marine heatwaves (MHWs), which are causing irreversible ecological changes. As a result, the enhancement of ecosystem resilience to disturbances has become a critical research and socio-political priority. Although there is substantial documentation of MHW-induced mass mortalities and thermal tolerance thresholds of key species, multifactorial mechanisms that help marine species and coastal ecosystems to resist and recover from MHWs are not well understood. RES2HEAT aims to fill this gap through a comparative, multidisciplinary approach, studying two contrasting Mediterranean habitats. We will investigate how various factors acting at different ecological levels affect the resilience, including both resistance and recovery capacity, of coastal ecosystems to MHWs. Specific objectives are: (1) evaluate differential resilience of communities and species to MHWs by analysing long-term changes in community and habitat complexity and developing a new index to quantify habitat complexity; (2) explore plasticity and heritable components of phenotypic variation of key species in response to thermal stress through common-garden and reciprocal transplant experiments with populations from varying thermal histories; and (3) characterize the genetic structure and connectivity among and within populations of key species to understand their ecology, including local dispersal, reproductive biology, and gene pool stability, using next-generation sequencing and demo-genetic methods. RES2HEAT integrates innovative and traditional methods, including long-term and regional data series, experiments, demographic sampling, novel underwater photogrammetry techniques, ecological indices, and genomics. The findings will be synthesized to provide key actionable recommendations for managing, conserving, and restoring coastal ecosystems in the context of CC.